Rolling cam actuated piezoelectric voltage source



Sept. 3, 1969 o. a. PARKINSON 3,469,119

ROLLING CAM ACTUA'IED PIEZOELECTRIC VOLTAGE SOURCE Filed Aug. 22, 1966INVENTOR. DAVID B. PARKINSON FIG.3- WWW/14k ATTORNEY United StatesPatent 3,469,119 ROLLING CAM ACTUATED PIEZOELECTRIC VOLTAGE SOURCE DavidB. Parkinson, Cleveland Heights, Ohio, assignor to Clevite Corporation,a corporation of Ohio Continuation-impart of application Ser. No.541,550, Apr. 11, 1966. This application Aug. 22, 1966, Ser. No. 574,103

Int. Cl. H02n 1/04 US. Cl. 3108.7 15 Claims ABSTRACT OF THE DISCLOSUREAn electric voltage source having a frame with piezoelectric elementslocated therein. A rolling cam contact within the frame for compressingand rotating the piezoelectric element therein to generate a voltage.

This invention relates generally to a piezoelectric voltage source and,more particularly, to a rolling cam actuated piezoelectric igniteradapted to be employed for igniting a wide variety of gas fired productssuch as outdoor barbecues, camp stoves, infrared heaters, ranges, hotwater tanks, outdoor lights and the like.

The present application is a continuation-in-part of application Ser.No. 541,550, filed Apr. 11, 1966, assigned to the same assignee, and nowabandoned.

In the prior art the voltage sources have been manifestly bulky,required too much effort to operate and were relatively expensive tofabricate. Although these devices have achieved a fairly wide acclaimfor their versatility over and above more conventional igniters and forthe negligible amount of maintenance required, the commercial acceptancehas been on a rather moderate scale.

It is therefore the primary object of this invention to provide apiezoelectric voltage source which exhibits a superior mechanicalefficiency over the products of the piror art, and more specifically inwhich a mechanical advantage system is utilized enabling the reductionof the force which must be applied to actuate the device by as much as a5 to 1 ratio.

It is a more specific object of the invention to provide a device of thetype above described in which a rolling contact mechanism is utilized,obviating the need for sliding surfaces, to obtain an improvedmechanical advantage and a more efiicient piezoelectric igniter.

An aspect of the present invention resides in the provision of apiezoelectric voltage source which includes a frame havinglongitudinally spaced abutments rigid against displacement. A stack ofpiezoelectric elements is disposed between the abutments. The stack ofelements has a first and second end face and a longitudinal axis normalthereto; the first end face bears against one of the abutments while thesecond end face is spaced relative to and faces the other abutment. Arolling cam mechanism is interposed, in bearing relation, between thesecond end face and the said other abutment. An actuating mechanism forrotating the cam mechanism relative to the second end face and the saidother abutment is effective to cause the frame to move angularlyrelative to the stack of piezoelectric elements and compress the same inthe longitudinal direction against the first named abutment to generatea voltage.

For a better understanding of the present invention, together with otherand further objects thereof, reference is had to the followingdescription taken in connection with the accompanying drawings, and itsscope will be pointed out in the appended claims.

In the drawings:

3,469 ,1 l9 Patented Sept. 23, 1969 "ice FIGURE 1 is an exploded view ofthe invention shown in perspective;

FIGURE 2 is a front view of the piezoelectric igniter, with the outercasing removed, illustrating the relatively unstressed position of thepiezoelectric assembly;

FIGURES 2a and 2b are views similar to FIGURE 2 illustrating additionaloperating characteristics;

FIGURE 3 is a side view of the piezoelectric element voltage source ascompletely assembled; and

FIGURE 4 is an enlarged cross sectional view of the rolling cam with camportions thereof exaggerated for illustrative purposes.

Referring now to the drawings, there is shown in FIG- URES l to 3 aframe 10 formed as a relatively flat structure having a longitudinallyextending, irregularly contoured, cut-out 11 for receiving a stack ofpiezoelectric elements 12 therein. The frame 10 is composed of ametallic material which is capable of withstanding longitudinal forcesbetween spaced portions upon working of the device as hereinafterfurther delineated.

In the preferred embodiment the stack of piezoelectric elements 12 arecomprised of, but not limited to, two cylindrical ceramic elements 14and 16 composed of barium titanate, lead titanate zirconate or similarpolycrystalline materials. Preferably, the elements are encapsulated,except for the end faces, with silicon rubber or similar material, notshown.

The elements are end electroded and polarized parallel to their axis bymeans of their electrodes. They are assembled in such a manner that theymay be said to be mechanically in series and electrically in parallel.Squeezing the elements in the longitudinal direction, i.e., parallel tothe axis of polarization, generates a high voltage potential at thecenter electrode 18 which in the form of a circular metallic late isinterposed between the elements 14 and 16. A suitable cable 20 extendstherefrom. The planes of the end faces of the stack 12 are parallel withregards to each other and the longitudinal axis of the stack 12 extendsnormal thereto.

One end face of the stack of elements 12 and more particularly ofelement 14 thereof bears against a little metallic plate or shoe 22which has an H-like configuration and is suitably seated in acomplementary cut-out formed in frame 10. Seated in the lower end of thecutout 11 of frame 10 and between the shoe 22 is a wedge-like structure24. The wedge 24 has a cylindrical surface and the peak thereof is inbearing contact with shoe 22. An effort is made to have the line contactbetween the wedge 24 and the shoe 22 coincide as nearly as possible withthe center line of the elements. In the longitudinal direction the wedge24 is slightly tapered for reasons which will hereinafter become moreapparent. The shoe 22, which incidentally also serves as an electricalground in the circuit, together with the wedge 24 are considered part ofthe abutment structure of frame 10 although these components do haveadditional functions.

At the opposite end of the stack 12 and more particularly between theend face of element 16 and the frame 10 there is interposed a smallmetallic plate 26 adapted for distributing the load applied upon thestack of elements 12. Another H-like metallic shoe 28 is seated in theextreme end of opening 11 in the frame 10 remote from the first namedH-like shoe 22 and securely abuts the frame. More particularly, each ofthe two H-like shoes 22 and 28, anchors, because of their projections,e.g., see 30, each individual plate to the frame and transverse movementthereof relative to the frame is prevented. Interposed between thelongitudinally spaced members 26 and 28 is a rolling cam member 32. Thecam 32 is an elongated rod-like structure and extends transverselythrough the frame and is generally formed of a cylindrical rod butincludes an out-of-round portion disposed in the area adjacent to andbetween the plate 26 and shoe 28.

Referring now specifically to FIGURE 4, the rolling cam 32 is fabricatedfrom cylindrical stock and the full diameter is identified as D Theroller cam 32 is provided with flat spots 33 on the peripheral surfaceand with cylindrical portions of gradually decreasing radius leading upto and merging into the flat spots. The flat spots are arranged in sucha manner that in the relaxed position of elements 12, the flat surfacesof each spot extend parallel to the adjacent cam follower surfaces ofshoe 28 and plate 26. Each cylindrical portion, exclusive of the flatspot, describes a peripheral segment of less than 90' degrees. Thediameter D across the flat spots 33 represents the smallest diameter ofthe cam. The portions removed in forming the cam are shown in outlineform.

In order to provide a proper support for the cam member 32 and tofacilitate the actuation thereof, there is provided a casing 34 formedof sheet metal or like material, one end thereof having a rectangularslot 36 adapted to receive the end 38 of frame and to restrain the sametherein. The opposite end of the casing 34 is U-shaped, see 40, andfolded back around the other end of the frame 10. The U-shaped portion40 of the casing 34 is provided with two openings which are axiallyaligned to receive in each opening one axial end portion of the rod-likecam member 32. To maintain the cam 32 as well as the members 26 and 28in a predetermined location, two circular washers 47 are mounted aboutthe cam and interposed between each transverse end of plate 26 and shoe28, and the respective portion of the U-shaped portion 40 of the casing34. One end of the rod-like cam 32 extending through the opening,illustrated on the left hand side in FIGURE 3, see 44, is turned at aright angle to limit the axial freedom of movement of the cam. Theopposite end of the cam 32 extends through the other opening, see 43,and is adapted to receive a lever 46 fixedly to the cam by means of aset screw, not shown.

Due to manufacturing tolerances a variation in assembled length mayexist in the stack of elements and the cooperating parts 22, 24, 26, 32and 28, therefore wedge 24 serves as an adjustment and precompressiondevice and is fabricated with a very small taper (shown in exaggeratedform, see FIGURE 3). In the exemplary embodiment the taper isapproximately 2. The wedge 24 is sufliciently long to compensate for thevarious tolerance conditions. In order to facilitate the assembly of thedevice the casing 34 is provided with an opening 50 through which thewedge 24 may initially protrude during assembly. After the wedge hasbeen moved transversely relative to the frame 10 to establish the properrelationship between the various parts, the unused portions thereof maybe cut off so that the end face adjacent the opening 50 will be more orless flush with the plane of the casing 34 adjacent thereto.

-In the preferred embodiment, the members 22, 24, 26, 28 and 32 are allfabricated of hardened steel.

As shown in FIGURE 2, the assembly of elements 12 maintains normally aslightly slanted or off-center position relative to the frame 10. Uponactuation of the lever 46 the assembly is caused to be moved angularlyabout the wedge 24 in a counterclockwise direction, i.e., towards thecentral axis of the device. Simultaneously, in the preferred embodiment,the frame 10 moves angularly in a clockwise direction. FIGURE 2aillustrates a position in which the assembly and the frame havetravelled the same distance, but in opposite directions, and are nowsymmetrically aligned. The rotation or angular movement of the elements12 is about a rotational axis lying in a plane parallel to the planeforming the end face of the element adjacent to member 22. FIGURE 2bshows the extreme operating position of the frame and the assembly.

The FIGURES 2 to 2b pre-suppose that the cam rotates about a fixed axis.However, it is entirely possible to let the cam move in which caseeither the assembly 12 or frame 10 is held stationary.

In operation, the cable 20 is placed in operative proximity to acombustible material which is to be ignited and a gap (not shown) isestablished in conjunction with a cable leading to ground. The lever 46is either manually, or by a linkage not shown, depressed, which in turncauses the cam 32 to roll about its axis thereby expanding the distancebetween the plates 26 and 28. Such expansion causes members 26 and 28 toyield to the force applied thereto and move in opposite directions asshown by the arrows in FIGURE 4. The stack of elements 12 bearing at oneend against the peak of wedge 24 is caused to move angularly asdiscussed above, together with the plate 26, about the peak of thewedge. The shoe 28 together with all those parts rigidly connectedtherewith, e.g., frame 10, moves in a direction opposite to that ofplate 26. The bottom portion 38 of frame 10 is suitably anchored in slot36 of casing 34 to permit such movement. The operation of the deviceresults in relative movement between the frame 10, the assembly 12 andthe casing 34. Expansion of the longitudinal distance between thestructures 26 and 28 places a high compressive force upon the ceramicelement assembly effective to generate and establish a potential on thecenter electrode 18. The device may be utilized without moving theassembly 12 and frame 10 through the complete operational cycle as shownin FIG- URES 2 to 2b. For some applications it will sufiice to rotatethe lever 46 only a fraction of the built-in operational capability.

While there have been described what are at present considered to be thepreferred embodiments of this invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madetherein without departing from the invention, and it is aimed,therefore, in the appended claims to cover all such changes andmodifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. A piezoelectric voltage source, comprising: frame means havinglongitudinally spaced abutments rigid against displacement;piezoelectric element means disposed between said abutments and havingfirst and second end faces and a longitudinal axis normal thereto; saidfirst end face being disposed in bearing relation against one of saidabutments, said second end face being spaced relative to and facing theother abutment; rolling contact means interposed, in bearing relation,between said second end face and the said other abutment; and actuatingmeans for rotating said cam means relative to said second end face andthe said other abutment to effect relative rotary translational movementsubstantially angular to said longitudinal axis between said frame meansand said element means, the rotational axis of the translationalmovement lying in a plane substantially parallel to the plane formingthe second end face of said element means, to compress the element meansin the longitudinal direction against the first named abutment togenerate a voltage.

2. A piezoelectric voltage source according to claim 1, wherein thelongitudinal axis of said cam means extends at right angle to the saidaxis of said element means and the actuating means is rigidly secured tosaid cam means.

3. A piezoelectric voltage source according to claim 1, wherein saidframe means includes a wedge disposed in bearing relation to the firstend face of said element means and having a rounded surface facing saidend face, the peak thereof being in line contact with the end face ofsaid element means and coinciding substantially with the central axis ofsaid element means.

4. A piezoelectric voltage source according to claim 3, wherein saidwedge is slightly tapered along its axis of elongation.

5. A piezoelectric voltage source according to claim 2, wherein said cammeans is longitudinally elongated and extends transverse relative tosaid frame.

6. A piezoelectric voltage source according to claim 2, wherein said cammeans is a generally circular rod having a flat spot and a portion ofsuccessively larger diameter extending therefrom on each segment of theperiphery facing said second end face and the said other abutment.

7. A piezoelectric voltage source according to claim 5, wherein saidframe means includes a relatively flat structural member having alongitudinally extending cut-out for receiving the element meanstherein.

8. A piezoelectric voltage source according to claim 7, wherein saidframe means includes a stationary casing adapted for movably receivingone end of said structural member, the opposite end of said casing beingU-shaped and spacedly telescoped over the other end of said structuralmember.

9. A piezoelectric voltage source according to claim 8, wherein said cammeans extends across, through, and is rotatably mounted about saidU-shaped portion.

10. A piezoelectric voltage source according to claim 1, whereinrotation of said cam means is effective to move at least portions ofsaid frame means and said element means in opposite directions.

11. A piezoelectric voltage source according to claim 1, whereinrotation of said cam means is elfective to move said element meansangularly about the first mentioned abutment.

12. A piezoelectric voltage source according to claim 1, whereinrotation of said cam means is effective to move at least portions ofsaid frame means angularly relative to said element means.

13. A piezoelectric voltage source according to claim 11, wherein thelongitudinal axis of said element means is normally angularly offsetfrom the longitudinal axis of said frame means.

14. A piezoelectric voltage source, comprising: frame means havinglongitudinally spaced abutments rigid against displacement;piezoelectric element means disposed between said abutments and havingfirst and second end faces and a longitudinal axis normal thereto; saidfirst end face being disposed in bearing relation against one of saidabutments, said second end face being spaced relative to and facing theother abutment; rolling contact compressing means interposed, in bearingrelation, between said second end face and the said other abutment; andactuating means for rotating portions of said compressing means relativeto said second end face and the said other abutment to effect relativetranslation movement substantially perpendicular to said longitudinalaxis between said frame means and said element means, to compress theelement means in the longitudinal direction against the first namedabutment to generate a voltage.

15. A piezoelectric voltage source according to claim 14, wherein saidrolling contact compressing means includes a stationary memberpositioned in bearing relation to the said other abutment, and arotatable member engaging said stationary member and being positioned inbearing relation to said second end face.

References Cited UNITED STATES PATENTS 3,350,608 10/1967 Maltner 317963,262,019 7/1966 Maltner 3108.7 3,211,069 10/1964 Rixton 11.5 3,118,0741/ 1964 Josephson 3 l0--8.7 3,114,059 12/1963 Hulferd 310-8] 3,082,3333/1963 Hulferd 3l08.7 3,295,024 12/1966 Newman 3108.7 3,211,949 10/ 1965Slaymaker 310-8.7 3,101,420 8/ 1963 Hufferd 3 l08.7

FOREIGN PATENTS 712,803 7/ 1954 Great Britain.

J. D. MILLER, Primary Examiner US. Cl. X.R.

Notice of Adverse Decisions in Interferences In Interference No. 97,388involving Patent No. 3,469,155, H. W. Van Beek, PUNCH-THROUGH MEANSINTEGRATED WITH MOS TYPE DE- VICES F OR PROTECTION AGAINST INSULATIONLAYER BREAK- DOWN, final judgment adverse to the patentee was renderedDec. 29, 1972, as to claims 1-8.

[Official Gazette May 92, 1973.]

